Advanced usage

While this package is designed to work with the request-based super-globals, it
is in no way limited to just those inputs. ReadonlyTypedMap is a class that
can provide a type-safe interface to any KeyedTraversable value including
arbitary arrays and collection objects.

This allows you to use it for values that aren't ordinarly typed. For example,
you could use it to provide a typed interface for a returned row from a
database.